Porous biocarrier-enhanced biodegradation of crude oil contaminated soil |
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| Authors: | Yuting Liang Xu Zhang Dongjuan Dai Guanghe Li |
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| Affiliation: | 1. Joint Research Centre for Protective Infrastructure Technology and Environmental Green Bioprocess, School of Environmental and Municipal Engineering, Tianjin Chengjian University, China and School of Civil and Environmental Engineering, University of Technology Sydney, Australia;2. Tianjin Key Laboratory of Aquatic Science and Technology, Tianjin Chengjian University, Jinjing Road 26, Tianjin 300384, China;3. Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney Sydney, NSW 2007, Australia;4. School of Environmental and Municipal Engineering, Xi''an University of Architecture and Technology, Xi''an 710055, China |
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| Abstract: | Soil contamination with crude oil from petrochemicals and oil exploitation is an important worldwide issue. Comparing available remediation techniques, bioremediation is widely considered to be a cost-effective choice; however, slow degradation of crude oil is a common problem due to the low numbers of bacteria capable of degrading petroleum hydrocarbons and the low bioavailability of contaminants in soil. To promote crude oil removal, biocarrier for immobilization of indigenous hydrocarbon-degrading bacteria was developed using porous materials such as activated carbon and zeolite. Microbial biomass reached 1010 cells g?1 on activated carbon and 106 cells g?1 on zeolite. Total microbial and dehydrogenase activities were approximately 12 times and 3 times higher, respectively, in activated carbon than in zeolite. High microbial colonization by spherical and rod shapes were observed for the 5–20 μm thick biofilm on the outer surface of both biocarriers using electronic microscopy. Based on batch-scale experiments containing free-living bacterial cultures and activated carbon biocarrier into crude oil contaminated soil, biocarrier enhanced the biodegradation of crude oil, with 48.89% removal, compared to natural attenuation with 13.0% removal, biostimulation (nutrient supplement only) with 26.3% removal, and bioaugmentation (free-living bacteria) with 37.4% removal. In addition, the biocarrier increased the bacterial population to 108 cells g?1 dry soil and total microbial activity to 3.5 A490. A hypothesis model was proposed to explain the mechanism: the biocarrier improved the oxygen, nutrient mass transfer and water holding capacity of the soil, which were the limiting factors for biodegradation of non-aqueous phase liquid (NAPL) contaminants such as crude oil in soil.Scientific relevanceThis study explored the role of biocarrier in enhancing biodegradation of hydrophobic contaminants such as crude oil, and discussed the function of biocarrier in improving oxygen mass transfer and soil water holding capacity, etc. |
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